A fundamental parameter in communication network systems comprising High Speed Uplink Data Access (HSUPA) operation is the noise rise threshold. Its purpose is to limit the amount of noise rise generated by the HSUPA users so that coverage for all services is maintained. An excessive noise rise causes a cell in such a communication network to shrink (cell breathing) something that could lead to that User Equipments (UE) distant to the Radio Base Station (RBS) experience poor uplink quality or even drop their connections.
The current best-practice is to set the noise rise threshold to a fixed value. This value should be selected as a good trade-off between HSUPA capacity and peak-rates on one hand and probability of uplink (UL) coverage in the cell on the other hand. Since the UL coverage probability is cell specific this analysis needs to be done on a per cell basis.
However, there are some problems with the current solutions. Firstly, the process of finding a good trade-off for the setting of the noise rise threshold in a cell is cumbersome, requiring an analysis of the coverage situation in each cell. Moreover, as the network evolves, e.g. new sites are added, new subscriber behaviour is introduced etc., the coverage situation in the cell will change, so that the process of finding a good trade-off must be repeated.
Further, even if a noise rise threshold is maintained in each cell in the network these noise rise thresholds are still set to fixed values. As a consequence, during time periods when no or few UEs are close to an uplink coverage limit, the uplink spectrum may be under-utilized, leading to decreased HSUPA capacity and peak-rates. Vice versa, during time periods when many UEs are close to an uplink coverage limit the uplink spectrum may be over-utilized leading to poor uplink quality or dropped calls.